Integrating groundwater response function into the Jarvis-type model for Populus popularis transpiration simulations

Abstract

Shallow groundwater is a critical water resource for sustaining vegetation growth in arid and semi-arid environments and affects stand transpiration (T) dynamics. However, it is still difficult to quantify the impact of groundwater on T. Here, we introduced a novel groundwater response function in the Jarvis-type model (referred to as MJSG) and tested its performance using Populus popularis sapflow data over two main growing seasons (2018–2019). The results showed that the performance of the MJSG model depended on groundwater level. Specifically, when groundwater table depth was within 1.2–2.0 m, the precision of daily T simulation by the MJSG model was higher than that by the MJS model without groundwater response function over two years, with an increase in Nash-Sutcliffe Efficiency (NSE) from 0.787 to 0.825. Furthermore, in contrast to the MJS model, the MJSG model could better capture the diurnal course of T in 10:00–16:00, with a significant increase in NSE from 0.592 to 0.706. The improvement allows a more accurately estimate of tree water use under shallow groundwater fluctuations, which will help broaden the ecohydrological application of the Jarvis-type model to similar areas.

Keywords

• Tree sap flow
• Shallow groundwater
• Jarvis-Stewart model
• Arid area